Method for the total gasification of wet bituminous fuels



Feb. 3, 1931. I H. HILLEBRAND 1,791,411

METHOD FOR THE TOTAL GASIFICATION 0F WET BITUMINOUS FUELS Filed Sept. 5, 1924 Patented Feb. 3, 1931 PATENT OFFICE WARN HILLEBRAN D, OF"BERLIN-FRIEDRICHSHAFEN, GERMAN Y :MJETHOD FOR THE TOTAL GASIFICATION 0F WET BITUMINOUS FUELS Application filed September 3, 1924, SerialNo. 735,692, and in Germany January 27, 1922.

It has previously been proposed to gasify solid fuels in a gas generator by means of a current of water gas passed continuously through the gas generator and a heating de- 5 vice such as a recuperator, or a regenerator, in such manner that in the heating device the circulating current of gas is supplied with the necessary heat for the water gas reaction, and then discharges same in the gas generator. At the same time the amount of steam required for generating the water gas is introduced into the generator from the exterior, water gas thus being generated in a continuous manner. The heating device and generator are heated in a known manner, the current of gas thus making a complete circuit through the generator on the one hand and through the heating device on the other hand, the same being heated in the heating device, and cooled in the gas generator by the endothermic water gas reaction. continuous operation is efl'ectedwith the aid of suitable means for conveying the gas such as exhausters, blowers or steam injectors.

the supp-l pipe.

The cii culating current of gas should be introduced to the conveying means at a temperature little less than the temperature of the uppermost layer of fuel. If with the great expansion of the hot gas for conveyance to be possible at all, it would be necessary for the temperature in the generator to be kept below the most desirable reaction temperature so that the production of gas of any great value is quite impossible, although Water cooling is employed for the exhausters or blowers. The generation of water gas from coke requires, for example, that the entering gas has a temperature of about 1200 C. and that the outgoing gas has a temperature of about 800 (3., Whilst water-cooled exhausters only operate up to a temperature of about 450 6., which temperature moreover is considerably above the most desirable temperature about 200 C. for drawing oif the gas from the heater.

to overcome all these difficulties, however, there still exists the disadvantage of having to employ control valves for the circulating The The gas as generated is drawn off through Were it possible current of gas heated in the regenerator. With the high gas temperature, moreover, an unfavorable ratio for mixing steam and gas results in the blower. The current ofgas would, therefore, in every case leave the generator at a temperature which is too low with regard to the desired efficiency of the generator, and too high in relation to the most favorable temperature for withdrawing from the heater, i. e., in relation to the desired efficiency of the heater.

According to the invention, the heat is preferably introduced in such manner, that the current leaving the gasifying zone with a correspondingly high temperature is cooled down to a temperature suitable for conveyance through the exhausters, by discharging its heat preferably for thegeneration of steam or for distilling purposes. The second disadvantage referred to is avoided by the fact that a current is branched off from the circulating current within the regenerator, and is employed for heating the regenerative device.

In this manner, in addition to the advantage of elimination of switching devices for the heated gas, substantial improvements are attained in the uninterrupted water gas generation. While otherwise in the case of such plants a special furnace is required for each regenerative chamber, which must be con ncctedor disconnected for each chamber upon every change in the gas, the regulation and determination of the amount of gas required for heating the cooled chamber in correct proportion to the amount of gas generated being thus rendered more difiicult; in the case of this invention on the other hand the particular amount of gas combusted corresponds exactly in pressure and composition to the particular amount of water gas generated, the' manipulation of the generator being thus substantially facilitated. Particularly with the current of gas branched off for combustion the possibility exists of eliminating from the operation a definite amount of steam without special drying, by employing a mixture of gas and steam for combusting the same, which mixture also enters into the gasifying device. In this manner a preliminary drying with all the devices necessary therefor may be entirely dispensed with in the case of fuels with average moisture content, while these in the case of fuels with a higher moisture content are smaller and cheaper than is represented by the amount of steam taken in the regenerator combustion.

As furthermore, in the case of this invention, water gas is employed for heating the gas chambers, the commingling of steam will prevent the forming of flames, and a greater uniformity of combustion is ensured.

In further embodiments of the invention parts of the plant subjected to high temperatures are built into a recess in the core of the gas-generating chamber or regenerator chambers, in such manner that the heat radiation is taken up by the wall bounding the recess.

The invention is illustrated in the acc0mpanying drawings, in which The figure is a view partly in vertical section in diagrammatical form through the plant for the generation of water gas.

The two regenerator chambers 1, 2, each possess an air induction alternately closable by valves 3, 4, and each gas inlet alternately closed by valves 5, 6 and gas outlet alternately closed by slide valves 7, 8. These, as shown, may be connected in a known manner with a common flue, or may each be formed as a stack. Both chambers are interconnected by passages 9, 9, and with the passage 10, which opens into the gasifying chamber 11. In the case of very moist fuels such as wet bituminous fuels a distilling chamber is arranged above this in a known manner, above which moreover, a preliminary dryer 13 is built if it is desired to avoid special condensing devices for the moisture in excess of the amount of gasifying steam required.

The parts descrlbed possess the customary fuel charging and ash removing devices. These are merely shown diagrammatically in the drawing. and are not specifically indicated. The circulating current of gas 14 enters into the chamber 1 through the valve 5, and is heated here to 10001200 (3., and passes through the passages 9, 10,-into the gasifier 11. In the passage 9 a part 15 of the gas current is branched ofl', partly because the gas current is under the pressure of a fan or the like 16, and partly by suction through the stack draft. The amount divided off is regulated in a known manner by the valve 8. The amount of the circulating gas current 14 is regulated in a certain proportion to the amount 15 divided off by means of slide valves 17 18. The combustion air is introduced to the branched off gas 15 through the valve 4. The flame sweeps through .the regenerative chamber 2 downwardly, heating the same. The cooled combustion gases are discharged through valve 8 in a known manner. The amount of water vaporized from the fuel in the gasifier 11 mixes with the circulating gas current 14, likewise the mixture of distillation gas, tar vapor and steam from the remaining carbon and moisture which is formed from fuel in the distilling chamber 12. The tar is withdrawn in-a known manner in a vapor state and admixed by means of the fan 16 prior to the entrance of the gas current 14 into the chamber 1. The vapor formed in the preliminary dryer 13 is discharged at 20, and ashes collect in the pan 30. A portion of the gas coming from the top zone 11 and passing through the valve 13 is led by a conduit 13*- to the drier 13.

The part of the gas current 14 rendered superfluous by the formation of fresh gas passes off through collecting pipe 19.

The operation is capable of regulation within the widest possible limits with regard to the desired amount of gas and the temperature of the individual parts by adjustment of the valves 17, 18, 19*, regulating the gas generation in correct relation to the valves 3, 4, 5, 6, 7, 8 controlling the heating of the regenerators. The valves 17, 18, 19 may be connected with the valves 3 to 8 in such manner that for the passage of a certain amount of gas the latter are restricted in opening by stops, which control the adjustment of the valves 17, 18, 19. Reference numeral 19 indicates a collecting main with a valve 19.

For changin over the gas, air and draft the valves 3, 5% and 4, 6, 8, are brought into the reversed positions as shown in the drawing, i. e., valves 4, 5 and 8 are closed and valves 3, 6 and 7 opened.

In order, upon change in the gas, air and draft, to prevent the useful water-gas contained in chamber 1 to pass into the flue, and the inert combustion gases contained in chamber 2 to pass into the gasifying chamber 11, a special device may be provided for purging out the chambers. For this purpose, upon changing over from the position shown into the reversed position, the valves 5 and 21 are closed, and the valve 22 opened, which latter valve is provided on the conduit 23 supplied with water vapor or steam from the preliminary drfyer 13. The steam rises in the chamber 1, orcing the lighter water gas very quickly into the gasifier 11 and into the chamber 2, the air Valve 4 of which is closed very shortly after the opening of the valve 22. The steam also very quickly sweeps out the chamber 2, forcing the produots of combustion through the valve 8 into the flue. This purging process is completed in a few seconds. The valves 8 and 22 are now closed, and valves 3, 6 and 7 and 24 opened, the gas circulation now occurring within the regenerative chambers 1 and 2 in reversed order. The gas generation is not materially interrupted by the purging process. The pressure of the fan 16, interrupted during the purging process, is replaced by the steam pressure from the preliminary dryer 13.

The invention makes possible a shortening of the gas connection for thehot current between the regenerator chambers and the generator to the smallest possible degree.

v WhatIclaimis:

A method for the total gasification of wet bituminous fuels; which comprises heating alternately operated regenerative chambers by burning a portion of recirculated gas, su-

perheating a mixture of recirculated gas and steam in one of the heated regenerative chambers, passing the heated recirculated gas and steam upwardly into a ga'sification zone of a fuel bed and thereby regenerating water gas,

1 passing a portion of the generated Water gas and recirculated gas through a superposeddistillation zone of the fuel bed and thereby distilling gases and vapors from the fuel, passing another portion of the generated water gas and recirculated gas in heat exchange with the wet fuel and to a collecting main, and recirculatin the distillation gases and vapors through tfie regenerative chamer. In testimony-whereof I have afixed my signature.

HERMANN HELEBRAND.

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